package admin

import (
	"testing"
	"time"
)

func TestPercentChange(t *testing.T) {
	if s := percentChange(0, 10); s != "+0%" {
		t.Fatalf("prev0")
	}
	if s := percentChange(10, 15); s == "" {
		t.Fatalf("empty")
	}
}

func TestPreviousWindow(t *testing.T) {
	s := time.Date(2025, 1, 1, 0, 0, 0, 0, time.Local)
	e := s.Add(7 * 24 * time.Hour).Add(-time.Second)
	ps, pe := previousWindow(s, e)
	if !pe.Before(s) {
		t.Fatalf("pe not before start")
	}
	if ps.After(pe) {
		t.Fatalf("ps after pe")
	}
}

func TestDaysBetween(t *testing.T) {
	s := time.Date(2025, 1, 1, 0, 0, 0, 0, time.Local)
	e := time.Date(2025, 1, 03, 23, 59, 59, 0, time.Local)
	ds := daysBetween(s, e)
	if len(ds) != 3 {
		t.Fatalf("expect3")
	}
}

func TestParseSalesTrendRange_PrefersStartEnd(t *testing.T) {
	now := time.Date(2026, 3, 3, 12, 0, 0, 0, time.UTC)
	s, e := parseSalesTrendRange("week", "2026-01-01", "2026-01-10", now, nil)

	if !s.Equal(time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)) {
		t.Fatalf("unexpected start: %v", s)
	}
	if !e.Equal(time.Date(2026, 1, 10, 23, 59, 59, 0, time.UTC)) {
		t.Fatalf("unexpected end: %v", e)
	}
}

func TestParseSalesTrendRange_AliasAndAllFallback(t *testing.T) {
	now := time.Date(2026, 3, 3, 12, 0, 0, 0, time.UTC)

	sWeek, eWeek := parseSalesTrendRange("week", "", "", now, nil)
	if !eWeek.Equal(now) {
		t.Fatalf("week end should be now")
	}
	if sWeek.Sub(eWeek) != -7*24*time.Hour {
		t.Fatalf("week should be 7 days")
	}

	sMonth, eMonth := parseSalesTrendRange("month", "", "", now, nil)
	if !eMonth.Equal(now) {
		t.Fatalf("month end should be now")
	}
	if sMonth.Sub(eMonth) != -30*24*time.Hour {
		t.Fatalf("month should be 30 days")
	}

	sAllFallback, eAllFallback := parseSalesTrendRange("all", "", "", now, nil)
	if !eAllFallback.Equal(now) {
		t.Fatalf("all fallback end should be now")
	}
	if sAllFallback.Sub(eAllFallback) != -30*24*time.Hour {
		t.Fatalf("all fallback should be 30 days")
	}

	allStart := time.Date(2025, 1, 15, 10, 0, 0, 0, time.UTC)
	sAll, eAll := parseSalesTrendRange("all", "", "", now, &allStart)
	if !sAll.Equal(time.Date(2025, 1, 15, 0, 0, 0, 0, time.UTC)) {
		t.Fatalf("all start should align to date start, got: %v", sAll)
	}
	if !eAll.Equal(now) {
		t.Fatalf("all end should be now")
	}
}

func TestParseSalesTrendRange_CustomSpanCap(t *testing.T) {
	now := time.Date(2026, 3, 3, 12, 0, 0, 0, time.UTC)
	s, e := parseSalesTrendRange("custom", "2025-01-01", "2026-12-31", now, nil)

	expectedStart := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
	expectedEnd := expectedStart.Add(365 * 24 * time.Hour).Add(-time.Second)
	if !s.Equal(expectedStart) {
		t.Fatalf("unexpected custom start: %v", s)
	}
	if !e.Equal(expectedEnd) {
		t.Fatalf("unexpected custom end: %v", e)
	}
}

func TestShouldUseMonthlyGranularityForAll(t *testing.T) {
	start := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
	endLong := start.Add(181 * 24 * time.Hour)
	endShort := start.Add(180 * 24 * time.Hour)

	if !shouldUseMonthlyGranularityForAll("all", "day", start, endLong) {
		t.Fatalf("expected monthly for all with >180 days")
	}
	if shouldUseMonthlyGranularityForAll("all", "day", start, endShort) {
		t.Fatalf("should not switch for exactly 180 days")
	}
	if shouldUseMonthlyGranularityForAll("week", "day", start, endLong) {
		t.Fatalf("non-all rangeType should not switch")
	}
	if shouldUseMonthlyGranularityForAll("all", "month", start, endLong) {
		t.Fatalf("non-day granularity should not switch")
	}
}